export default {
  namespaced: true,
  
  state:()=>({
    // 购物车的数组，用来存储购物车中每个商品的信息对象
    // 每个商品的信息对象，都包含如下 6 个属性：
    // { goods_id, goods_name, goods_price, goods_count, goods_small_logo, goods_state }
    cart: JSON.parse(uni.getStorageSync('cart') || '[]')
  }),
  
  mutations:{
    addToCart (state, goods) {
      
     const findResult = state.cart.find(x => x.goods_id === goods.goods_id)
     
     if(!findResult){
       state.cart.push(goods)
     } else {
       findResult.goods_count ++
     }
    // 通过 commit 方法，调用 m_cart 命名空间下的 saveToStorage 方法
     this.commit('m_cart/saveToStorage')
    },
    saveToStorage(state) {
      uni.setStorageSync('cart', JSON.stringify(state.cart))
    },
    updateGoodsState(state, goods) {
     const findResult = state.cart.find(x => x.goods_id === goods.goods_id)

     if(findResult) {
     findResult.goods_state = goods.goods_state
       
       this.commit('m_cart/saveToStorage')
     }
    },
    // 更新购物车中的商品数量
    updateGoodsCount(state, goods) {
      // 根据 goods_id 查询购物车中对应商品的信息对象
    const findResult = state.cart.find(x => x.goods_id === goods.goods_id)
    if(findResult) {
       // 更新对应商品的数量
      findResult.goods_count = goods.goods_count
       // 持久化存储到本地
      this.commit('m_cart/saveToStorage')
    }
    },
    updateAllGoodsState(state, newState) {
      state.cart.forEach(x => x.goods_state = newState)
      this.commit('m_cart/saveToStorage')
    }
  },
  
  getters:{
    total(state) {
      // let c = 0
      // state.cart.forEach(x => c += x.goods_count)
      // return c
     return state.cart.reduce((total, item) => total += item.goods_count, 0)
    },
    checkedCount(state) {
     return state.cart.filter(x => x.goods_state).reduce((total, item) => total += item.goods_count, 0)
    },
    checkedGoodsAmount(state) {
     return state.cart.filter(x => x.goods_state).reduce((total, item) => total += item.goods_price * item.goods_count, 0).toFixed(2)
    }
  }
}